.grammar-page {
  --grammar-font: 'Onest', -apple-system, BlinkMacSystemFont, sans-serif;
  --grammar-primary: var(--primary-600);
  --grammar-primary-dark: var(--primary-700);
  --grammar-success: var(--success-500);
  --grammar-surface: #ffffff;
  --grammar-surface-alt: #f8fafc;
  --grammar-text: #0f172a;
  --grammar-text-muted: #64748b;
  --grammar-border: #e2e8f0;
  --grammar-radius: 16px;
  --grammar-radius-sm: 10px;

  font-family: var(--grammar-font);
  max-width: 900px;
  margin: 0 auto;
  padding: 0 1rem 3rem;
}

/* Breadcrumb */
.grammar-breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: var(--grammar-text-muted);
  margin-bottom: 1.5rem;
}

.grammar-breadcrumb a {
  color: var(--grammar-primary);
  text-decoration: none;
  font-weight: 500;
}

.grammar-breadcrumb a:hover {
  text-decoration: underline;
}

.grammar-breadcrumb svg {
  opacity: 0.5;
}

/* Hero */
.topics-hero {
  position: relative;
  background: linear-gradient(135deg, var(--primary-600) 0%, var(--primary-500) 50%, var(--primary-400) 100%);
  border-radius: var(--grammar-radius);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  overflow: hidden;
  color: #fff !important;
}

.topics-hero__bg-shapes {
  position: absolute;
  inset: 0;
  overflow: hidden;
  pointer-events: none;
}

.topics-hero .shape {
  position: absolute;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
}

.topics-hero .shape--1 {
  width: 150px;
  height: 150px;
  top: -50px;
  right: -30px;
  animation: float-1 18s ease-in-out infinite;
}

.topics-hero .shape--2 {
  width: 80px;
  height: 80px;
  bottom: -30px;
  left: 10%;
  animation: float-2 14s ease-in-out infinite;
}

@keyframes float-1 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(-15px, 15px) scale(1.05); }
}

@keyframes float-2 {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  50% { transform: translate(20px, -15px) rotate(8deg); }
}

.topics-hero__content {
  position: relative;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 1rem;
}

.topics-hero__header {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.topics-hero__icon {
  width: 52px;
  height: 52px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(10px);
}

.topics-hero__title {
  font-size: 1.5rem;
  font-weight: 700;
  margin: 0;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.topics-hero__subtitle {
  font-size: 0.875rem;
  margin: 0.25rem 0 0;
  opacity: 0.9;
}

.topics-hero__action {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.625rem 1.25rem;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 10px;
  color: #fff !important;
  text-decoration: none;
  font-size: 0.9375rem;
  font-weight: 600;
  backdrop-filter: blur(5px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  transition: all 0.2s ease;
}

.topics-hero__action:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: translateY(-2px);
  color: #fff !important;
}

/* Filter */
.topics-filter {
  background: var(--grammar-surface);
  border-radius: var(--grammar-radius-sm);
  padding: 1rem;
  margin-bottom: 1.5rem;
  border: 1px solid var(--grammar-border);
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.topics-filter__label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--grammar-text-muted);
}

.topics-filter__buttons {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.topics-filter__btn {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  padding: 0.5rem 0.875rem;
  background: var(--grammar-surface-alt);
  border: 1px solid var(--grammar-border);
  border-radius: 8px;
  color: var(--grammar-text);
  text-decoration: none;
  font-size: 0.8125rem;
  font-weight: 600;
  transition: all 0.2s ease;
}

.topics-filter__btn:hover {
  border-color: var(--grammar-primary);
  color: var(--grammar-primary);
}

.topics-filter__btn--active {
  background: var(--grammar-primary);
  border-color: var(--grammar-primary);
  color: #fff !important;
}

.topics-filter__btn--active:hover {
  color: #fff !important;
}

.topics-filter__btn--a.topics-filter__btn--active {
  background: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
  border-color: #3b82f6;
}

.topics-filter__btn--b.topics-filter__btn--active {
  background: linear-gradient(135deg, var(--warning-500) 0%, var(--danger-500) 100%);
  border-color: var(--danger-500);
}

.topics-filter__btn--c.topics-filter__btn--active {
  background: linear-gradient(135deg, #ec4899 0%, var(--primary-500) 100%);
  border-color: var(--primary-500);
}

.topics-filter__count {
  padding: 0.125rem 0.375rem;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 4px;
  font-size: 0.6875rem;
}

.topics-filter__btn:not(.topics-filter__btn--active) .topics-filter__count {
  background: var(--grammar-border);
  color: var(--grammar-text-muted);
}

/* Topics List */
.topics-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.topic-card {
  position: relative;
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1.25rem;
  background: var(--grammar-surface);
  border: 1px solid var(--grammar-border);
  border-radius: var(--grammar-radius-sm);
  text-decoration: none;
  color: inherit;
  transition: all 0.25s ease;
}

.topic-card:hover {
  border-color: var(--grammar-primary);
  transform: translateX(4px);
  box-shadow: 0 4px 12px rgba(var(--primary-600-rgb), 0.1);
}

.topic-card__level {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.875rem;
  font-weight: 700;
  color: #fff !important;
  flex-shrink: 0;
}

.topic-card__level--a {
  background: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
}

.topic-card__level--b {
  background: linear-gradient(135deg, var(--warning-500) 0%, var(--danger-500) 100%);
}

.topic-card__level--c {
  background: linear-gradient(135deg, #ec4899 0%, var(--primary-500) 100%);
}

.topic-card__content {
  flex: 1;
  min-width: 0;
}

.topic-card__title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--grammar-text);
  margin: 0 0 0.25rem;
  line-height: 1.3;
  word-break: break-word;
  overflow-wrap: anywhere;
}

.topic-card__subtitle {
  font-size: 0.8125rem;
  color: var(--grammar-text-muted);
  margin: 0;
  line-height: 1.3;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.topic-card__progress {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-shrink: 0;
}

.topic-card__progress-bar {
  width: 60px;
  height: 6px;
  background: rgba(var(--primary-600-rgb), 0.15);
  border-radius: 3px;
  overflow: hidden;
}

.topic-card__progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--grammar-primary) 0%, var(--primary-500) 100%);
  border-radius: 3px;
}

.topic-card__progress-text {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--grammar-primary);
  min-width: 24px;
}

.topic-card__status {
  flex-shrink: 0;
}

.topic-status {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.25rem 0.625rem;
  border-radius: 6px;
  font-size: 0.6875rem;
  font-weight: 600;
}

.topic-status--mastered {
  background: rgba(34, 197, 94, 0.1);
  color: var(--success-600);
}

.topic-status--confident {
  background: rgba(var(--info-500-rgb), 0.1);
  color: #2563eb;
}

.topic-status--learning {
  background: rgba(245, 158, 11, 0.1);
  color: #d97706;
}

.topic-status--started {
  background: rgba(var(--primary-600-rgb), 0.1);
  color: var(--grammar-primary);
}

.topic-status--new {
  background: var(--grammar-surface-alt);
  color: var(--grammar-text-muted);
}

.topic-card__meta {
  display: flex;
  align-items: center;
  gap: 0.375rem;
  font-size: 0.75rem;
  color: var(--grammar-text-muted);
  flex-shrink: 0;
}

.topic-card__arrow {
  color: var(--grammar-text-muted);
  opacity: 0;
  transition: all 0.25s ease;
  flex-shrink: 0;
}

.topic-card:hover .topic-card__arrow {
  opacity: 1;
  color: var(--grammar-primary);
}

/* Empty State */
.topics-empty {
  background: var(--grammar-surface);
  border-radius: var(--grammar-radius);
  border: 1px solid var(--grammar-border);
  padding: 4rem 2rem;
  text-align: center;
}

.topics-empty__icon {
  color: var(--grammar-border);
  margin-bottom: 1rem;
}

.topics-empty__title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--grammar-text);
  margin: 0 0 0.5rem;
}

.topics-empty__desc {
  font-size: 0.875rem;
  color: var(--grammar-text-muted);
  margin: 0 0 1rem;
}

.topics-empty__levels {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  flex-wrap: wrap;
}

.topics-empty__level-link {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 1rem;
  background: var(--grammar-surface-alt);
  border: 1px solid var(--grammar-border);
  border-radius: 8px;
  color: var(--grammar-primary);
  text-decoration: none;
  font-size: 0.875rem;
  font-weight: 600;
  transition: all 0.2s ease;
}

.topics-empty__level-link:hover {
  border-color: var(--grammar-primary);
  background: rgba(var(--primary-600-rgb), 0.06);
}

.topics-empty__level-link--all {
  background: var(--grammar-primary);
  border-color: var(--grammar-primary);
  color: #fff !important;
}

.topics-empty__level-link--all:hover {
  background: var(--grammar-primary-dark);
  color: #fff !important;
}

/* Animations */
@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.topics-hero { animation: slideUp 0.4s ease-out; }
.topics-filter { animation: slideUp 0.4s ease-out 0.1s both; }
.topics-list { animation: slideUp 0.4s ease-out 0.15s both; }
.topics-empty { animation: slideUp 0.5s ease-out; }

.topic-card {
  animation: slideUp 0.35s ease-out both;
}

.topic-card:nth-child(1) { animation-delay: 0.1s; }
.topic-card:nth-child(2) { animation-delay: 0.15s; }
.topic-card:nth-child(3) { animation-delay: 0.2s; }
.topic-card:nth-child(4) { animation-delay: 0.25s; }
.topic-card:nth-child(5) { animation-delay: 0.3s; }
.topic-card:nth-child(6) { animation-delay: 0.35s; }
.topic-card:nth-child(7) { animation-delay: 0.4s; }
.topic-card:nth-child(8) { animation-delay: 0.45s; }
.topic-card:nth-child(9) { animation-delay: 0.5s; }
.topic-card:nth-child(10) { animation-delay: 0.55s; }

/* Responsive */
@media (max-width: 640px) {
  .grammar-page {
    padding: 0 0.75rem 2rem;
  }

  .topics-hero {
    padding: 1.25rem;
  }

  .topics-hero__content {
    flex-direction: column;
    align-items: flex-start;
  }

  .topics-hero__action {
    width: 100%;
    justify-content: center;
  }

  .topics-filter {
    flex-direction: column;
    align-items: flex-start;
  }

  .topics-filter__buttons {
    width: 100%;
  }

  .topics-filter__btn {
    flex: 1;
    justify-content: center;
    min-width: 0;
  }

  .topic-card {
    flex-wrap: wrap;
    padding: 1rem;
  }

  .topic-card__content {
    flex: 1 1 calc(100% - 60px);
    order: 1;
  }

  .topic-card__level {
    order: 0;
  }

  .topic-card__progress {
    order: 3;
    width: 100%;
    margin-top: 0.5rem;
  }

  .topic-card__progress-bar {
    flex: 1;
  }

  .topic-card__status {
    order: 2;
    margin-left: auto;
  }

  .topic-card__meta {
    display: none;
  }

  .topic-card__arrow {
    display: none;
  }
}